<div class="container">
  <div class="square">
    <span style="--i:0;"></span>
    <span style="--i:1;"></span>
    <span style="--i:2;"></span>
    <span style="--i:3;"></span>
  </div>
  <div class="square">
    <span style="--i:0;"></span>
    <span style="--i:1;"></span>
    <span style="--i:2;"></span>
    <span style="--i:3;"></span>
  </div>
  <div class="square">
    <span style="--i:0;"></span>
    <span style="--i:1;"></span>
    <span style="--i:2;"></span>
    <span style="--i:3;"></span>
  </div>
</div>
<style>
/* From Uiverse.io by codebykay101 - Tags: animation, neon, css, effects */
.container {
  position: relative;
  width: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
}

.container .square {
  position: absolute;
  width: 200px;
  height: 200px;
}

.container .square:nth-child(2) {
  transform: translate(-25%, -25%) rotateX(180deg);
  filter: hue-rotate(60deg);
}

.container .square:nth-child(3) {
  transform: translate(25%, 25%) rotate(180deg);
  filter: hue-rotate(180deg);
}

.container .square::before {
  content: '';
  position: absolute;
  width: 20px;
  height: 20px;
  background: #0f0;
  box-shadow: 0 0 0 8px #0f03, 0 0 0 15px #0f01;
  animation: animateSquare 4s linear infinite;
}

@keyframes animateSquare {
  0% {
    transform: translate(2px,2px);
  }

  25% {
    transform: translate(178px,2px);
  }

  50% {
    transform: translate(178px,178px);
  }

  75% {
    transform: translate(2px,178px);
  }

  100% {
    transform: translate(2px,2px);
  }
}

.container .square span {
  position: absolute;
  inset: 10px;
  overflow: hidden;
  transform: rotate(calc(90deg * var(--i)));
}

.container .square span::before {
  content: '';
  position: absolute;
  width: 100%;
  height: 4px;
  background: #0f0;
  transform: translateX(-100%);
  animation: animate 4s linear infinite;
  animation-delay: calc(1s * var(--i));
}

@keyframes animate {
  0% {
    transform: translateX(-100%);
  }

  50%,100% {
    transform: translateX(100%);
  }
}
</style>
